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<?php |
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namespace Vikpe; |
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class HtmlHeadingNormalizer |
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{ |
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public static function demote($html, $levels) |
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{ |
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return self::normalize($html, $levels); |
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} |
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public static function promote($html, $levels) |
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{ |
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return self::normalize($html, -$levels); |
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} |
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private static function normalize($html, $levels) |
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{ |
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if (!self::containsHeadings($html)) { |
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return $html; |
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} |
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$domDocument = new \DOMDocument(); |
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$domDocument->loadHTML($html); |
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$originalHeadings = self::getHeadings($domDocument); |
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$normalizedHeadings = self::normalizeHeadings($originalHeadings, $levels); |
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self::replaceHeadings( |
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$originalHeadings, |
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$normalizedHeadings |
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); |
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return $domDocument->saveHTML(); |
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} |
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private static function getHeadings(\DOMDocument $domDocument) |
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{ |
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$tagNames = array('h1', 'h2', 'h3', 'h4', 'h5', 'h6'); |
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$headings = array(); |
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foreach ($tagNames as $tagName) { |
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foreach ($domDocument->getElementsByTagName($tagName) as $heading) { |
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$headings[] = $heading; |
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} |
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} |
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return $headings; |
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} |
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private static function normalizeHeadings(array $originalHeadings, $levelDelta) |
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{ |
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$normalizedHeadings = array(); |
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foreach ($originalHeadings as $heading) { |
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$currentLevel = self::tagNameToLevel($heading->tagName); |
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$normalizedLevel = $currentLevel + $levelDelta; |
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$normalizedHeadings[] = self::cloneHeading($heading, $normalizedLevel); |
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} |
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return $normalizedHeadings; |
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} |
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private static function replaceHeadings(array $needles, array $replacements) |
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{ |
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foreach ($needles as $i => $needle) { |
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$needle->parentNode->replaceChild($replacements[$i], $needle); |
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} |
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} |
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private static function containsHeadings($html) |
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{ |
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$headingNeedle = '<h'; |
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$containsHeadings = (false !== stripos($html, $headingNeedle)); |
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return $containsHeadings; |
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} |
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private static function tagNameToLevel($tagName) |
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{ |
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return substr($tagName, 1); |
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} |
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private static function levelToTagName($level) |
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{ |
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return 'h'.$level; |
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} |
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private static function cloneHeading(\DOMElement $sourceHeading, $level = null) |
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{ |
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if (null !== $level) { |
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$tagName = self::levelToTagName($level); |
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} else { |
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$tagName = $sourceHeading->tagName; |
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} |
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$targetHeading = $sourceHeading->parentNode->ownerDocument->createElement($tagName); |
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self::copyAttributes($sourceHeading, $targetHeading); |
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self::moveChildNodes($sourceHeading, $targetHeading); |
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return $targetHeading; |
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} |
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private static function copyAttributes(\DOMElement $source, \DOMElement $target) |
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{ |
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foreach ($source->attributes as $attribute) { |
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$target->setAttribute($attribute->name, $attribute->value); |
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} |
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} |
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private static function moveChildNodes(\DOMElement $source, \DOMElement $target) |
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{ |
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while ($source->hasChildNodes()) { |
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// appendChild() actually moves the childNode |
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$target->appendChild($source->childNodes->item(0)); |
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} |
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} |
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} |
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